/* libFLAC - Free Lossless Audio Codec library
 * Copyright (C) 2001,2002,2003,2004,2005,2006,2007  Josh Coalson
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 *
 * - Neither the name of the Xiph.org Foundation nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#if HAVE_CONFIG_H
    #include <config.h>
#endif

#include <stdlib.h>
#include <string.h>

#include "private/metadata.h"

#include "public/assert_flac.h"
#include "share/alloc.h"


/****************************************************************************
 *
 * Local routines
 *
 ***************************************************************************/

/* copy bytes:
 *  from = nullptr  && bytes = 0
 *       to <- nullptr
 *  from != nullptr && bytes > 0
 *       to <- copy of from
 *  else ASSERT
 * malloc error leaves 'to' unchanged
 */
static FLAC__bool copy_bytes_(FLAC__byte** to, const FLAC__byte* from, unsigned bytes)
{
    FLAC__ASSERT(0 != to);
    if (bytes > 0 && 0 != from)
    {
        FLAC__byte* x;
        if (0 == (x = (FLAC__byte*)safe_malloc_(bytes)))
            return false;
        memcpy(x, from, bytes);
        *to = x;
    }
    else
    {
        FLAC__ASSERT(0 == from);
        FLAC__ASSERT(bytes == 0);
        *to = 0;
    }
    return true;
}

#if 0 /* UNUSED */
/* like copy_bytes_(), but free()s the original '*to' if the copy succeeds and the original '*to' is non-nullptr */
static FLAC__bool free_copy_bytes_(FLAC__byte** to, const FLAC__byte* from, unsigned bytes)
{
    FLAC__byte* copy;
    FLAC__ASSERT(0 != to);
    if (copy_bytes_(&copy, from, bytes))
    {
        if (*to)
            free(*to);
        *to = copy;
        return true;
    }
    else
        return false;
}
#endif

/* reallocate entry to 1 byte larger and add a terminating NUL */
/* realloc() failure leaves entry unchanged */
static FLAC__bool ensure_null_terminated_(FLAC__byte** entry, unsigned length)
{
    FLAC__byte* x = (FLAC__byte*)safe_realloc_add_2op_(*entry, length, /*+*/ 1);
    if (0 != x)
    {
        x[length] = '\0';
        *entry = x;
        return true;
    }
    else
        return false;
}

/* copies the NUL-terminated C-string 'from' to '*to', leaving '*to'
 * unchanged if malloc fails, free()ing the original '*to' if it
 * succeeds and the original '*to' was not nullptr
 */
static FLAC__bool copy_cstring_(char** to, const char* from)
{
    char* copy = _strdup(from);
    FLAC__ASSERT(to);
    if (copy)
    {
        if (*to)
            free(*to);
        *to = copy;
        return true;
    }
    else
        return false;
}

static FLAC__bool copy_vcentry_(FLAC__StreamMetadata_VorbisComment_Entry* to, const FLAC__StreamMetadata_VorbisComment_Entry* from)
{
    to->length = from->length;
    if (0 == from->entry)
    {
        FLAC__ASSERT(from->length == 0);
        to->entry = 0;
    }
    else
    {
        FLAC__byte* x;
        FLAC__ASSERT(from->length > 0);
        if (0 == (x = (FLAC__byte*)safe_malloc_add_2op_(from->length, /*+*/ 1)))
            return false;
        memcpy(x, from->entry, from->length);
        x[from->length] = '\0';
        to->entry = x;
    }
    return true;
}

static FLAC__bool copy_track_(FLAC__StreamMetadata_CueSheet_Track* to, const FLAC__StreamMetadata_CueSheet_Track* from)
{
    memcpy(to, from, sizeof(FLAC__StreamMetadata_CueSheet_Track));
    if (0 == from->indices)
    {
        FLAC__ASSERT(from->num_indices == 0);
    }
    else
    {
        FLAC__StreamMetadata_CueSheet_Index* x;
        FLAC__ASSERT(from->num_indices > 0);
        if (0 == (x = (FLAC__StreamMetadata_CueSheet_Index*)safe_malloc_mul_2op_(from->num_indices, /*times*/ sizeof(FLAC__StreamMetadata_CueSheet_Index))))
            return false;
        memcpy(x, from->indices, from->num_indices * sizeof(FLAC__StreamMetadata_CueSheet_Index));
        to->indices = x;
    }
    return true;
}

static void seektable_calculate_length_(FLAC__StreamMetadata* object)
{
    FLAC__ASSERT(0 != object);
    FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_SEEKTABLE);

    object->length = object->data.seek_table.num_points * FLAC__STREAM_METADATA_SEEKPOINT_LENGTH;
}

static FLAC__StreamMetadata_SeekPoint * seekpoint_array_new_(unsigned num_points)
{
    FLAC__StreamMetadata_SeekPoint* object_array;

    FLAC__ASSERT(num_points > 0);

    object_array = (FLAC__StreamMetadata_SeekPoint*)safe_malloc_mul_2op_(num_points, /*times*/ sizeof(FLAC__StreamMetadata_SeekPoint));

    if (0 != object_array)
    {
        unsigned i;
        for (i = 0; i < num_points; i++)
        {
            object_array[i].sample_number = FLAC__STREAM_METADATA_SEEKPOINT_PLACEHOLDER;
            object_array[i].stream_offset = 0;
            object_array[i].frame_samples = 0;
        }
    }

    return object_array;
}

static void vorbiscomment_calculate_length_(FLAC__StreamMetadata* object)
{
    unsigned i;

    FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);

    object->length = (FLAC__STREAM_METADATA_VORBIS_COMMENT_ENTRY_LENGTH_LEN) / 8;
    object->length += object->data.vorbis_comment.vendor_string.length;
    object->length += (FLAC__STREAM_METADATA_VORBIS_COMMENT_NUM_COMMENTS_LEN) / 8;
    for (i = 0; i < object->data.vorbis_comment.num_comments; i++)
    {
        object->length += (FLAC__STREAM_METADATA_VORBIS_COMMENT_ENTRY_LENGTH_LEN / 8);
        object->length += object->data.vorbis_comment.comments[i].length;
    }
}

static FLAC__StreamMetadata_VorbisComment_Entry * vorbiscomment_entry_array_new_(unsigned num_comments)
{
    FLAC__ASSERT(num_comments > 0);

    return (FLAC__StreamMetadata_VorbisComment_Entry*)safe_calloc_(num_comments, sizeof(FLAC__StreamMetadata_VorbisComment_Entry));
}

static void vorbiscomment_entry_array_delete_(FLAC__StreamMetadata_VorbisComment_Entry* object_array, unsigned num_comments)
{
    unsigned i;

    FLAC__ASSERT(0 != object_array && num_comments > 0);

    for (i = 0; i < num_comments; i++)
        if (0 != object_array[i].entry)
            free(object_array[i].entry);

    if (0 != object_array)
        free(object_array);
}

static FLAC__StreamMetadata_VorbisComment_Entry * vorbiscomment_entry_array_copy_(const FLAC__StreamMetadata_VorbisComment_Entry* object_array, unsigned num_comments)
{
    FLAC__StreamMetadata_VorbisComment_Entry* return_array;

    FLAC__ASSERT(0 != object_array);
    FLAC__ASSERT(num_comments > 0);

    return_array = vorbiscomment_entry_array_new_(num_comments);

    if (0 != return_array)
    {
        unsigned i;

        for (i = 0; i < num_comments; i++)
        {
            if (!copy_vcentry_(return_array + i, object_array + i))
            {
                vorbiscomment_entry_array_delete_(return_array, num_comments);
                return 0;
            }
        }
    }

    return return_array;
}

static FLAC__bool vorbiscomment_set_entry_(FLAC__StreamMetadata* object, FLAC__StreamMetadata_VorbisComment_Entry* dest, const FLAC__StreamMetadata_VorbisComment_Entry* src, FLAC__bool copy)
{
    FLAC__byte* save;

    FLAC__ASSERT(0 != object);
    FLAC__ASSERT(0 != dest);
    FLAC__ASSERT(0 != src);
    FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);
    FLAC__ASSERT((0 != src->entry && src->length > 0) || (0 == src->entry && src->length == 0));

    save = dest->entry;

    if (0 != src->entry && src->length > 0)
    {
        if (copy)
        {
            /* do the copy first so that if we fail we leave the dest object untouched */
            if (!copy_vcentry_(dest, src))
                return false;
        }
        else
        {
            /* we have to make sure that the string we're taking over is null-terminated */

            /*
             * Stripping the const from src->entry is OK since we're taking
             * ownership of the pointer.  This is a hack around a deficiency
             * in the API where the same function is used for 'copy' and
             * 'own', but the source entry is a const pointer.  If we were
             * precise, the 'own' flavor would be a separate function with a
             * non-const source pointer.  But it's not, so we hack away.
             */
            if (!ensure_null_terminated_((FLAC__byte**)(&src->entry), src->length))
                return false;
            *dest = *src;
        }
    }
    else
    {
        /* the src is null */
        *dest = *src;
    }

    if (0 != save)
        free(save);

    vorbiscomment_calculate_length_(object);
    return true;
}

static int vorbiscomment_find_entry_from_(const FLAC__StreamMetadata* object, unsigned offset, const char* field_name, unsigned field_name_length)
{
    unsigned i;

    FLAC__ASSERT(0 != object);
    FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);
    FLAC__ASSERT(0 != field_name);

    for (i = offset; i < object->data.vorbis_comment.num_comments; i++)
    {
        if (FLAC__metadata_object_vorbiscomment_entry_matches(object->data.vorbis_comment.comments[i], field_name, field_name_length))
            return (int)i;
    }

    return -1;
}

static void cuesheet_calculate_length_(FLAC__StreamMetadata* object)
{
    unsigned i;

    FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_CUESHEET);

    object->length = (
        FLAC__STREAM_METADATA_CUESHEET_MEDIA_CATALOG_NUMBER_LEN +
        FLAC__STREAM_METADATA_CUESHEET_LEAD_IN_LEN +
        FLAC__STREAM_METADATA_CUESHEET_IS_CD_LEN +
        FLAC__STREAM_METADATA_CUESHEET_RESERVED_LEN +
        FLAC__STREAM_METADATA_CUESHEET_NUM_TRACKS_LEN
        ) / 8;

    object->length += object->data.cue_sheet.num_tracks * (
        FLAC__STREAM_METADATA_CUESHEET_TRACK_OFFSET_LEN +
        FLAC__STREAM_METADATA_CUESHEET_TRACK_NUMBER_LEN +
        FLAC__STREAM_METADATA_CUESHEET_TRACK_ISRC_LEN +
        FLAC__STREAM_METADATA_CUESHEET_TRACK_TYPE_LEN +
        FLAC__STREAM_METADATA_CUESHEET_TRACK_PRE_EMPHASIS_LEN +
        FLAC__STREAM_METADATA_CUESHEET_TRACK_RESERVED_LEN +
        FLAC__STREAM_METADATA_CUESHEET_TRACK_NUM_INDICES_LEN
        ) / 8;

    for (i = 0; i < object->data.cue_sheet.num_tracks; i++)
    {
        object->length += object->data.cue_sheet.tracks[i].num_indices * (
            FLAC__STREAM_METADATA_CUESHEET_INDEX_OFFSET_LEN +
            FLAC__STREAM_METADATA_CUESHEET_INDEX_NUMBER_LEN +
            FLAC__STREAM_METADATA_CUESHEET_INDEX_RESERVED_LEN
            ) / 8;
    }
}

static FLAC__StreamMetadata_CueSheet_Index * cuesheet_track_index_array_new_(unsigned num_indices)
{
    FLAC__ASSERT(num_indices > 0);

    return (FLAC__StreamMetadata_CueSheet_Index*)safe_calloc_(num_indices, sizeof(FLAC__StreamMetadata_CueSheet_Index));
}

static FLAC__StreamMetadata_CueSheet_Track * cuesheet_track_array_new_(unsigned num_tracks)
{
    FLAC__ASSERT(num_tracks > 0);

    return (FLAC__StreamMetadata_CueSheet_Track*)safe_calloc_(num_tracks, sizeof(FLAC__StreamMetadata_CueSheet_Track));
}

static void cuesheet_track_array_delete_(FLAC__StreamMetadata_CueSheet_Track* object_array, unsigned num_tracks)
{
    unsigned i;

    FLAC__ASSERT(0 != object_array && num_tracks > 0);

    for (i = 0; i < num_tracks; i++)
    {
        if (0 != object_array[i].indices)
        {
            FLAC__ASSERT(object_array[i].num_indices > 0);
            free(object_array[i].indices);
        }
    }

    if (0 != object_array)
        free(object_array);
}

static FLAC__StreamMetadata_CueSheet_Track * cuesheet_track_array_copy_(const FLAC__StreamMetadata_CueSheet_Track* object_array, unsigned num_tracks)
{
    FLAC__StreamMetadata_CueSheet_Track* return_array;

    FLAC__ASSERT(0 != object_array);
    FLAC__ASSERT(num_tracks > 0);

    return_array = cuesheet_track_array_new_(num_tracks);

    if (0 != return_array)
    {
        unsigned i;

        for (i = 0; i < num_tracks; i++)
        {
            if (!copy_track_(return_array + i, object_array + i))
            {
                cuesheet_track_array_delete_(return_array, num_tracks);
                return 0;
            }
        }
    }

    return return_array;
}

static FLAC__bool cuesheet_set_track_(FLAC__StreamMetadata* object, FLAC__StreamMetadata_CueSheet_Track* dest, const FLAC__StreamMetadata_CueSheet_Track* src, FLAC__bool copy)
{
    FLAC__StreamMetadata_CueSheet_Index* save;

    FLAC__ASSERT(0 != object);
    FLAC__ASSERT(0 != dest);
    FLAC__ASSERT(0 != src);
    FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_CUESHEET);
    FLAC__ASSERT((0 != src->indices && src->num_indices > 0) || (0 == src->indices && src->num_indices == 0));

    save = dest->indices;

    /* do the copy first so that if we fail we leave the object untouched */
    if (copy)
    {
        if (!copy_track_(dest, src))
            return false;
    }
    else
    {
        *dest = *src;
    }

    if (0 != save)
        free(save);

    cuesheet_calculate_length_(object);
    return true;
}


/****************************************************************************
 *
 * Metadata object routines
 *
 ***************************************************************************/

FLAC_API FLAC__StreamMetadata * FLAC__metadata_object_new(FLAC__MetadataType type)
{
    FLAC__StreamMetadata* object;

    if (type > FLAC__MAX_METADATA_TYPE_CODE)
        return 0;

    object = (FLAC__StreamMetadata*)calloc(1, sizeof(FLAC__StreamMetadata));
    if (0 != object)
    {
        object->is_last = false;
        object->type = type;
        switch (type)
        {
            case FLAC__METADATA_TYPE_STREAMINFO:
                object->length = FLAC__STREAM_METADATA_STREAMINFO_LENGTH;
                break;
            case FLAC__METADATA_TYPE_PADDING:
                /* calloc() took care of this for us:
                   object->length = 0;
                 */
                break;
            case FLAC__METADATA_TYPE_APPLICATION:
                object->length = FLAC__STREAM_METADATA_APPLICATION_ID_LEN / 8;
                /* calloc() took care of this for us:
                   object->data.application.data = 0;
                 */
                break;
            case FLAC__METADATA_TYPE_SEEKTABLE:
                /* calloc() took care of this for us:
                   object->length = 0;
                   object->data.seek_table.num_points = 0;
                   object->data.seek_table.points = 0;
                 */
                break;
            case FLAC__METADATA_TYPE_VORBIS_COMMENT:
                object->data.vorbis_comment.vendor_string.length = (unsigned)strlen(FLAC__VENDOR_STRING);
                if (!copy_bytes_(&object->data.vorbis_comment.vendor_string.entry, (const FLAC__byte*)FLAC__VENDOR_STRING, object->data.vorbis_comment.vendor_string.length + 1))
                {
                    free(object);
                    return 0;
                }
                vorbiscomment_calculate_length_(object);
                break;
            case FLAC__METADATA_TYPE_CUESHEET:
                cuesheet_calculate_length_(object);
                break;
            case FLAC__METADATA_TYPE_PICTURE:
                object->length = (
                    FLAC__STREAM_METADATA_PICTURE_TYPE_LEN +
                    FLAC__STREAM_METADATA_PICTURE_MIME_TYPE_LENGTH_LEN + /* empty mime_type string */
                    FLAC__STREAM_METADATA_PICTURE_DESCRIPTION_LENGTH_LEN + /* empty description string */
                    FLAC__STREAM_METADATA_PICTURE_WIDTH_LEN +
                    FLAC__STREAM_METADATA_PICTURE_HEIGHT_LEN +
                    FLAC__STREAM_METADATA_PICTURE_DEPTH_LEN +
                    FLAC__STREAM_METADATA_PICTURE_COLORS_LEN +
                    FLAC__STREAM_METADATA_PICTURE_DATA_LENGTH_LEN +
                    0 /* no data */
                    ) / 8;
                object->data.picture.type = FLAC__STREAM_METADATA_PICTURE_TYPE_OTHER;
                object->data.picture.mime_type = 0;
                object->data.picture.description = 0;
                /* calloc() took care of this for us:
                   object->data.picture.width = 0;
                   object->data.picture.height = 0;
                   object->data.picture.depth = 0;
                   object->data.picture.colors = 0;
                   object->data.picture.data_length = 0;
                   object->data.picture.data = 0;
                 */
                /* now initialize mime_type and description with empty strings to make things easier on the client */
                if (!copy_cstring_(&object->data.picture.mime_type, ""))
                {
                    free(object);
                    return 0;
                }
                if (!copy_cstring_((char**)(&object->data.picture.description), ""))
                {
                    if (object->data.picture.mime_type)
                        free(object->data.picture.mime_type);
                    free(object);
                    return 0;
                }
                break;
            default:
                /* calloc() took care of this for us:
                   object->length = 0;
                   object->data.unknown.data = 0;
                 */
                break;
        }
    }

    return object;
}

FLAC_API FLAC__StreamMetadata * FLAC__metadata_object_clone(const FLAC__StreamMetadata* object)
{
    FLAC__StreamMetadata* to;

    FLAC__ASSERT(0 != object);

    if (0 != (to = FLAC__metadata_object_new(object->type)))
    {
        to->is_last = object->is_last;
        to->type = object->type;
        to->length = object->length;
        switch (to->type)
        {
            case FLAC__METADATA_TYPE_STREAMINFO:
                memcpy(&to->data.stream_info, &object->data.stream_info, sizeof(FLAC__StreamMetadata_StreamInfo));
                break;
            case FLAC__METADATA_TYPE_PADDING:
                break;
            case FLAC__METADATA_TYPE_APPLICATION:
                if (to->length < FLAC__STREAM_METADATA_APPLICATION_ID_LEN / 8)   /* underflow check */
                {
                    FLAC__metadata_object_delete(to);
                    return 0;
                }
                memcpy(&to->data.application.id, &object->data.application.id, FLAC__STREAM_METADATA_APPLICATION_ID_LEN / 8);
                if (!copy_bytes_(&to->data.application.data, object->data.application.data, object->length - FLAC__STREAM_METADATA_APPLICATION_ID_LEN / 8))
                {
                    FLAC__metadata_object_delete(to);
                    return 0;
                }
                break;
            case FLAC__METADATA_TYPE_SEEKTABLE:
                to->data.seek_table.num_points = object->data.seek_table.num_points;
                if (to->data.seek_table.num_points > SIZE_MAX / sizeof(FLAC__StreamMetadata_SeekPoint))   /* overflow check */
                {
                    FLAC__metadata_object_delete(to);
                    return 0;
                }
                if (!copy_bytes_((FLAC__byte**)&to->data.seek_table.points, (FLAC__byte*)object->data.seek_table.points, object->data.seek_table.num_points * sizeof(FLAC__StreamMetadata_SeekPoint)))
                {
                    FLAC__metadata_object_delete(to);
                    return 0;
                }
                break;
            case FLAC__METADATA_TYPE_VORBIS_COMMENT:
                if (0 != to->data.vorbis_comment.vendor_string.entry)
                {
                    free(to->data.vorbis_comment.vendor_string.entry);
                    to->data.vorbis_comment.vendor_string.entry = 0;
                }
                if (!copy_vcentry_(&to->data.vorbis_comment.vendor_string, &object->data.vorbis_comment.vendor_string))
                {
                    FLAC__metadata_object_delete(to);
                    return 0;
                }
                if (object->data.vorbis_comment.num_comments == 0)
                {
                    FLAC__ASSERT(0 == object->data.vorbis_comment.comments);
                    to->data.vorbis_comment.comments = 0;
                }
                else
                {
                    FLAC__ASSERT(0 != object->data.vorbis_comment.comments);
                    to->data.vorbis_comment.comments = vorbiscomment_entry_array_copy_(object->data.vorbis_comment.comments, object->data.vorbis_comment.num_comments);
                    if (0 == to->data.vorbis_comment.comments)
                    {
                        FLAC__metadata_object_delete(to);
                        return 0;
                    }
                }
                to->data.vorbis_comment.num_comments = object->data.vorbis_comment.num_comments;
                break;
            case FLAC__METADATA_TYPE_CUESHEET:
                memcpy(&to->data.cue_sheet, &object->data.cue_sheet, sizeof(FLAC__StreamMetadata_CueSheet));
                if (object->data.cue_sheet.num_tracks == 0)
                {
                    FLAC__ASSERT(0 == object->data.cue_sheet.tracks);
                }
                else
                {
                    FLAC__ASSERT(0 != object->data.cue_sheet.tracks);
                    to->data.cue_sheet.tracks = cuesheet_track_array_copy_(object->data.cue_sheet.tracks, object->data.cue_sheet.num_tracks);
                    if (0 == to->data.cue_sheet.tracks)
                    {
                        FLAC__metadata_object_delete(to);
                        return 0;
                    }
                }
                break;
            case FLAC__METADATA_TYPE_PICTURE:
                to->data.picture.type = object->data.picture.type;
                if (!copy_cstring_(&to->data.picture.mime_type, object->data.picture.mime_type))
                {
                    FLAC__metadata_object_delete(to);
                    return 0;
                }
                if (!copy_cstring_((char**)(&to->data.picture.description), (const char*)object->data.picture.description))
                {
                    FLAC__metadata_object_delete(to);
                    return 0;
                }
                to->data.picture.width = object->data.picture.width;
                to->data.picture.height = object->data.picture.height;
                to->data.picture.depth = object->data.picture.depth;
                to->data.picture.colors = object->data.picture.colors;
                to->data.picture.data_length = object->data.picture.data_length;
                if (!copy_bytes_((&to->data.picture.data), object->data.picture.data, object->data.picture.data_length))
                {
                    FLAC__metadata_object_delete(to);
                    return 0;
                }
                break;
            default:
                if (!copy_bytes_(&to->data.unknown.data, object->data.unknown.data, object->length))
                {
                    FLAC__metadata_object_delete(to);
                    return 0;
                }
                break;
        }
    }

    return to;
}

void FLAC__metadata_object_delete_data(FLAC__StreamMetadata* object)
{
    FLAC__ASSERT(0 != object);

    switch (object->type)
    {
        case FLAC__METADATA_TYPE_STREAMINFO:
        case FLAC__METADATA_TYPE_PADDING:
            break;
        case FLAC__METADATA_TYPE_APPLICATION:
            if (0 != object->data.application.data)
            {
                free(object->data.application.data);
                object->data.application.data = 0;
            }
            break;
        case FLAC__METADATA_TYPE_SEEKTABLE:
            if (0 != object->data.seek_table.points)
            {
                free(object->data.seek_table.points);
                object->data.seek_table.points = 0;
            }
            break;
        case FLAC__METADATA_TYPE_VORBIS_COMMENT:
            if (0 != object->data.vorbis_comment.vendor_string.entry)
            {
                free(object->data.vorbis_comment.vendor_string.entry);
                object->data.vorbis_comment.vendor_string.entry = 0;
            }
            if (0 != object->data.vorbis_comment.comments)
            {
                FLAC__ASSERT(object->data.vorbis_comment.num_comments > 0);
                vorbiscomment_entry_array_delete_(object->data.vorbis_comment.comments, object->data.vorbis_comment.num_comments);
            }
            break;
        case FLAC__METADATA_TYPE_CUESHEET:
            if (0 != object->data.cue_sheet.tracks)
            {
                FLAC__ASSERT(object->data.cue_sheet.num_tracks > 0);
                cuesheet_track_array_delete_(object->data.cue_sheet.tracks, object->data.cue_sheet.num_tracks);
            }
            break;
        case FLAC__METADATA_TYPE_PICTURE:
            if (0 != object->data.picture.mime_type)
            {
                free(object->data.picture.mime_type);
                object->data.picture.mime_type = 0;
            }
            if (0 != object->data.picture.description)
            {
                free(object->data.picture.description);
                object->data.picture.description = 0;
            }
            if (0 != object->data.picture.data)
            {
                free(object->data.picture.data);
                object->data.picture.data = 0;
            }
            break;
        default:
            if (0 != object->data.unknown.data)
            {
                free(object->data.unknown.data);
                object->data.unknown.data = 0;
            }
            break;
    }
}

FLAC_API void FLAC__metadata_object_delete(FLAC__StreamMetadata* object)
{
    FLAC__metadata_object_delete_data(object);
    free(object);
}

static FLAC__bool compare_block_data_streaminfo_(const FLAC__StreamMetadata_StreamInfo* block1, const FLAC__StreamMetadata_StreamInfo* block2)
{
    if (block1->min_blocksize != block2->min_blocksize)
        return false;
    if (block1->max_blocksize != block2->max_blocksize)
        return false;
    if (block1->min_framesize != block2->min_framesize)
        return false;
    if (block1->max_framesize != block2->max_framesize)
        return false;
    if (block1->sample_rate != block2->sample_rate)
        return false;
    if (block1->channels != block2->channels)
        return false;
    if (block1->bits_per_sample != block2->bits_per_sample)
        return false;
    if (block1->total_samples != block2->total_samples)
        return false;
    if (0 != memcmp(block1->md5sum, block2->md5sum, 16))
        return false;
    return true;
}

static FLAC__bool compare_block_data_application_(const FLAC__StreamMetadata_Application* block1, const FLAC__StreamMetadata_Application* block2, unsigned block_length)
{
    FLAC__ASSERT(0 != block1);
    FLAC__ASSERT(0 != block2);
    FLAC__ASSERT(block_length >= sizeof(block1->id));

    if (0 != memcmp(block1->id, block2->id, sizeof(block1->id)))
        return false;
    if (0 != block1->data && 0 != block2->data)
        return 0 == memcmp(block1->data, block2->data, block_length - sizeof(block1->id));
    else
        return block1->data == block2->data;
}

static FLAC__bool compare_block_data_seektable_(const FLAC__StreamMetadata_SeekTable* block1, const FLAC__StreamMetadata_SeekTable* block2)
{
    unsigned i;

    FLAC__ASSERT(0 != block1);
    FLAC__ASSERT(0 != block2);

    if (block1->num_points != block2->num_points)
        return false;

    if (0 != block1->points && 0 != block2->points)
    {
        for (i = 0; i < block1->num_points; i++)
        {
            if (block1->points[i].sample_number != block2->points[i].sample_number)
                return false;
            if (block1->points[i].stream_offset != block2->points[i].stream_offset)
                return false;
            if (block1->points[i].frame_samples != block2->points[i].frame_samples)
                return false;
        }
        return true;
    }
    else
        return block1->points == block2->points;
}

static FLAC__bool compare_block_data_vorbiscomment_(const FLAC__StreamMetadata_VorbisComment* block1, const FLAC__StreamMetadata_VorbisComment* block2)
{
    unsigned i;

    if (block1->vendor_string.length != block2->vendor_string.length)
        return false;

    if (0 != block1->vendor_string.entry && 0 != block2->vendor_string.entry)
    {
        if (0 != memcmp(block1->vendor_string.entry, block2->vendor_string.entry, block1->vendor_string.length))
            return false;
    }
    else if (block1->vendor_string.entry != block2->vendor_string.entry)
        return false;

    if (block1->num_comments != block2->num_comments)
        return false;

    for (i = 0; i < block1->num_comments; i++)
    {
        if (0 != block1->comments[i].entry && 0 != block2->comments[i].entry)
        {
            if (0 != memcmp(block1->comments[i].entry, block2->comments[i].entry, block1->comments[i].length))
                return false;
        }
        else if (block1->comments[i].entry != block2->comments[i].entry)
            return false;
    }
    return true;
}

static FLAC__bool compare_block_data_cuesheet_(const FLAC__StreamMetadata_CueSheet* block1, const FLAC__StreamMetadata_CueSheet* block2)
{
    unsigned i, j;

    if (0 != strcmp(block1->media_catalog_number, block2->media_catalog_number))
        return false;

    if (block1->lead_in != block2->lead_in)
        return false;

    if (block1->is_cd != block2->is_cd)
        return false;

    if (block1->num_tracks != block2->num_tracks)
        return false;

    if (0 != block1->tracks && 0 != block2->tracks)
    {
        FLAC__ASSERT(block1->num_tracks > 0);
        for (i = 0; i < block1->num_tracks; i++)
        {
            if (block1->tracks[i].offset != block2->tracks[i].offset)
                return false;
            if (block1->tracks[i].number != block2->tracks[i].number)
                return false;
            if (0 != memcmp(block1->tracks[i].isrc, block2->tracks[i].isrc, sizeof(block1->tracks[i].isrc)))
                return false;
            if (block1->tracks[i].type != block2->tracks[i].type)
                return false;
            if (block1->tracks[i].pre_emphasis != block2->tracks[i].pre_emphasis)
                return false;
            if (block1->tracks[i].num_indices != block2->tracks[i].num_indices)
                return false;
            if (0 != block1->tracks[i].indices && 0 != block2->tracks[i].indices)
            {
                FLAC__ASSERT(block1->tracks[i].num_indices > 0);
                for (j = 0; j < block1->tracks[i].num_indices; j++)
                {
                    if (block1->tracks[i].indices[j].offset != block2->tracks[i].indices[j].offset)
                        return false;
                    if (block1->tracks[i].indices[j].number != block2->tracks[i].indices[j].number)
                        return false;
                }
            }
            else if (block1->tracks[i].indices != block2->tracks[i].indices)
                return false;
        }
    }
    else if (block1->tracks != block2->tracks)
        return false;
    return true;
}

static FLAC__bool compare_block_data_picture_(const FLAC__StreamMetadata_Picture* block1, const FLAC__StreamMetadata_Picture* block2)
{
    if (block1->type != block2->type)
        return false;
    if (block1->mime_type != block2->mime_type && (0 == block1->mime_type || 0 == block2->mime_type || strcmp(block1->mime_type, block2->mime_type)))
        return false;
    if (block1->description != block2->description && (0 == block1->description || 0 == block2->description || strcmp((const char*)block1->description, (const char*)block2->description)))
        return false;
    if (block1->width != block2->width)
        return false;
    if (block1->height != block2->height)
        return false;
    if (block1->depth != block2->depth)
        return false;
    if (block1->colors != block2->colors)
        return false;
    if (block1->data_length != block2->data_length)
        return false;
    if (block1->data != block2->data && (0 == block1->data || 0 == block2->data || memcmp(block1->data, block2->data, block1->data_length)))
        return false;
    return true;
}

static FLAC__bool compare_block_data_unknown_(const FLAC__StreamMetadata_Unknown* block1, const FLAC__StreamMetadata_Unknown* block2, unsigned block_length)
{
    FLAC__ASSERT(0 != block1);
    FLAC__ASSERT(0 != block2);

    if (0 != block1->data && 0 != block2->data)
        return 0 == memcmp(block1->data, block2->data, block_length);
    else
        return block1->data == block2->data;
}

FLAC_API FLAC__bool FLAC__metadata_object_is_equal(const FLAC__StreamMetadata* block1, const FLAC__StreamMetadata* block2)
{
    FLAC__ASSERT(0 != block1);
    FLAC__ASSERT(0 != block2);

    if (block1->type != block2->type)
    {
        return false;
    }
    if (block1->is_last != block2->is_last)
    {
        return false;
    }
    if (block1->length != block2->length)
    {
        return false;
    }
    switch (block1->type)
    {
        case FLAC__METADATA_TYPE_STREAMINFO:
            return compare_block_data_streaminfo_(&block1->data.stream_info, &block2->data.stream_info);
        case FLAC__METADATA_TYPE_PADDING:
            return true; /* we don't compare the padding guts */
        case FLAC__METADATA_TYPE_APPLICATION:
            return compare_block_data_application_(&block1->data.application, &block2->data.application, block1->length);
        case FLAC__METADATA_TYPE_SEEKTABLE:
            return compare_block_data_seektable_(&block1->data.seek_table, &block2->data.seek_table);
        case FLAC__METADATA_TYPE_VORBIS_COMMENT:
            return compare_block_data_vorbiscomment_(&block1->data.vorbis_comment, &block2->data.vorbis_comment);
        case FLAC__METADATA_TYPE_CUESHEET:
            return compare_block_data_cuesheet_(&block1->data.cue_sheet, &block2->data.cue_sheet);
        case FLAC__METADATA_TYPE_PICTURE:
            return compare_block_data_picture_(&block1->data.picture, &block2->data.picture);
        default:
            return compare_block_data_unknown_(&block1->data.unknown, &block2->data.unknown, block1->length);
    }
}

FLAC_API FLAC__bool FLAC__metadata_object_application_set_data(FLAC__StreamMetadata* object, FLAC__byte* data, unsigned length, FLAC__bool copy)
{
    FLAC__byte* save;

    FLAC__ASSERT(0 != object);
    FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_APPLICATION);
    FLAC__ASSERT((0 != data && length > 0) || (0 == data && length == 0 && copy == false));

    save = object->data.application.data;

    /* do the copy first so that if we fail we leave the object untouched */
    if (copy)
    {
        if (!copy_bytes_(&object->data.application.data, data, length))
            return false;
    }
    else
    {
        object->data.application.data = data;
    }

    if (0 != save)
        free(save);

    object->length = FLAC__STREAM_METADATA_APPLICATION_ID_LEN / 8 + length;
    return true;
}

FLAC_API FLAC__bool FLAC__metadata_object_seektable_resize_points(FLAC__StreamMetadata* object, unsigned new_num_points)
{
    FLAC__ASSERT(0 != object);
    FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_SEEKTABLE);

    if (0 == object->data.seek_table.points)
    {
        FLAC__ASSERT(object->data.seek_table.num_points == 0);
        if (0 == new_num_points)
            return true;
        else if (0 == (object->data.seek_table.points = seekpoint_array_new_(new_num_points)))
            return false;
    }
    else
    {
        const size_t old_size = object->data.seek_table.num_points * sizeof(FLAC__StreamMetadata_SeekPoint);
        const size_t new_size = new_num_points * sizeof(FLAC__StreamMetadata_SeekPoint);

        /* overflow check */
        if ((size_t)new_num_points > SIZE_MAX / sizeof(FLAC__StreamMetadata_SeekPoint))
            return false;

        FLAC__ASSERT(object->data.seek_table.num_points > 0);

        if (new_size == 0)
        {
            free(object->data.seek_table.points);
            object->data.seek_table.points = 0;
        }
        else if (0 == (object->data.seek_table.points = (FLAC__StreamMetadata_SeekPoint*)realloc(object->data.seek_table.points, new_size)))
            return false;

        /* if growing, set new elements to placeholders */
        if (new_size > old_size)
        {
            unsigned i;
            for (i = object->data.seek_table.num_points; i < new_num_points; i++)
            {
                object->data.seek_table.points[i].sample_number = FLAC__STREAM_METADATA_SEEKPOINT_PLACEHOLDER;
                object->data.seek_table.points[i].stream_offset = 0;
                object->data.seek_table.points[i].frame_samples = 0;
            }
        }
    }

    object->data.seek_table.num_points = new_num_points;

    seektable_calculate_length_(object);
    return true;
}

FLAC_API void FLAC__metadata_object_seektable_set_point(FLAC__StreamMetadata* object, unsigned point_num, FLAC__StreamMetadata_SeekPoint point)
{
    FLAC__ASSERT(0 != object);
    FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_SEEKTABLE);
    FLAC__ASSERT(point_num < object->data.seek_table.num_points);

    object->data.seek_table.points[point_num] = point;
}

FLAC_API FLAC__bool FLAC__metadata_object_seektable_insert_point(FLAC__StreamMetadata* object, unsigned point_num, FLAC__StreamMetadata_SeekPoint point)
{
    int i;

    FLAC__ASSERT(0 != object);
    FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_SEEKTABLE);
    FLAC__ASSERT(point_num <= object->data.seek_table.num_points);

    if (!FLAC__metadata_object_seektable_resize_points(object, object->data.seek_table.num_points + 1))
        return false;

    /* move all points >= point_num forward one space */
    for (i = (int)object->data.seek_table.num_points - 1; i > (int)point_num; i--)
        object->data.seek_table.points[i] = object->data.seek_table.points[i - 1];

    FLAC__metadata_object_seektable_set_point(object, point_num, point);
    seektable_calculate_length_(object);
    return true;
}

FLAC_API FLAC__bool FLAC__metadata_object_seektable_delete_point(FLAC__StreamMetadata* object, unsigned point_num)
{
    unsigned i;

    FLAC__ASSERT(0 != object);
    FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_SEEKTABLE);
    FLAC__ASSERT(point_num < object->data.seek_table.num_points);

    /* move all points > point_num backward one space */
    for (i = point_num; i < object->data.seek_table.num_points - 1; i++)
        object->data.seek_table.points[i] = object->data.seek_table.points[i + 1];

    return FLAC__metadata_object_seektable_resize_points(object, object->data.seek_table.num_points - 1);
}

FLAC_API FLAC__bool FLAC__metadata_object_seektable_is_legal(const FLAC__StreamMetadata* object)
{
    FLAC__ASSERT(0 != object);
    FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_SEEKTABLE);

    return FLAC__format_seektable_is_legal(&object->data.seek_table);
}

FLAC_API FLAC__bool FLAC__metadata_object_seektable_template_append_placeholders(FLAC__StreamMetadata* object, unsigned num)
{
    FLAC__ASSERT(0 != object);
    FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_SEEKTABLE);

    if (num > 0)
        /* WATCHOUT: we rely on the fact that growing the array adds PLACEHOLDERS at the end */
        return FLAC__metadata_object_seektable_resize_points(object, object->data.seek_table.num_points + num);
    else
        return true;
}

FLAC_API FLAC__bool FLAC__metadata_object_seektable_template_append_point(FLAC__StreamMetadata* object, FLAC__uint64 sample_number)
{
    FLAC__StreamMetadata_SeekTable* seek_table;

    FLAC__ASSERT(0 != object);
    FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_SEEKTABLE);

    seek_table = &object->data.seek_table;

    if (!FLAC__metadata_object_seektable_resize_points(object, seek_table->num_points + 1))
        return false;

    seek_table->points[seek_table->num_points - 1].sample_number = sample_number;
    seek_table->points[seek_table->num_points - 1].stream_offset = 0;
    seek_table->points[seek_table->num_points - 1].frame_samples = 0;

    return true;
}

FLAC_API FLAC__bool FLAC__metadata_object_seektable_template_append_points(FLAC__StreamMetadata* object, FLAC__uint64 sample_numbers[], unsigned num)
{
    FLAC__ASSERT(0 != object);
    FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_SEEKTABLE);
    FLAC__ASSERT(0 != sample_numbers || num == 0);

    if (num > 0)
    {
        FLAC__StreamMetadata_SeekTable* seek_table = &object->data.seek_table;
        unsigned i, j;

        i = seek_table->num_points;

        if (!FLAC__metadata_object_seektable_resize_points(object, seek_table->num_points + num))
            return false;

        for (j = 0; j < num; i++, j++)
        {
            seek_table->points[i].sample_number = sample_numbers[j];
            seek_table->points[i].stream_offset = 0;
            seek_table->points[i].frame_samples = 0;
        }
    }

    return true;
}

FLAC_API FLAC__bool FLAC__metadata_object_seektable_template_append_spaced_points(FLAC__StreamMetadata* object, unsigned num, FLAC__uint64 total_samples)
{
    FLAC__ASSERT(0 != object);
    FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_SEEKTABLE);
    FLAC__ASSERT(total_samples > 0);

    if (num > 0 && total_samples > 0)
    {
        FLAC__StreamMetadata_SeekTable* seek_table = &object->data.seek_table;
        unsigned i, j;

        i = seek_table->num_points;

        if (!FLAC__metadata_object_seektable_resize_points(object, seek_table->num_points + num))
            return false;

        for (j = 0; j < num; i++, j++)
        {
            seek_table->points[i].sample_number = total_samples * (FLAC__uint64)j / (FLAC__uint64)num;
            seek_table->points[i].stream_offset = 0;
            seek_table->points[i].frame_samples = 0;
        }
    }

    return true;
}

FLAC_API FLAC__bool FLAC__metadata_object_seektable_template_append_spaced_points_by_samples(FLAC__StreamMetadata* object, unsigned samples, FLAC__uint64 total_samples)
{
    FLAC__ASSERT(0 != object);
    FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_SEEKTABLE);
    FLAC__ASSERT(samples > 0);
    FLAC__ASSERT(total_samples > 0);

    if (samples > 0 && total_samples > 0)
    {
        FLAC__StreamMetadata_SeekTable* seek_table = &object->data.seek_table;
        unsigned i, j;
        FLAC__uint64 num, sample;

        num = 1 + total_samples / samples; /* 1+ for the first sample at 0 */
        /* now account for the fact that we don't place a seekpoint at "total_samples" since samples are number from 0: */
        if (total_samples % samples == 0)
            num--;

        i = seek_table->num_points;

        if (!FLAC__metadata_object_seektable_resize_points(object, seek_table->num_points + (unsigned)num))
            return false;

        sample = 0;
        for (j = 0; j < num; i++, j++, sample += samples)
        {
            seek_table->points[i].sample_number = sample;
            seek_table->points[i].stream_offset = 0;
            seek_table->points[i].frame_samples = 0;
        }
    }

    return true;
}

FLAC_API FLAC__bool FLAC__metadata_object_seektable_template_sort(FLAC__StreamMetadata* object, FLAC__bool compact)
{
    unsigned unique;

    FLAC__ASSERT(0 != object);
    FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_SEEKTABLE);

    unique = FLAC__format_seektable_sort(&object->data.seek_table);

    return !compact || FLAC__metadata_object_seektable_resize_points(object, unique);
}

FLAC_API FLAC__bool FLAC__metadata_object_vorbiscomment_set_vendor_string(FLAC__StreamMetadata* object, FLAC__StreamMetadata_VorbisComment_Entry entry, FLAC__bool copy)
{
    if (!FLAC__format_vorbiscomment_entry_value_is_legal(entry.entry, entry.length))
        return false;
    return vorbiscomment_set_entry_(object, &object->data.vorbis_comment.vendor_string, &entry, copy);
}

FLAC_API FLAC__bool FLAC__metadata_object_vorbiscomment_resize_comments(FLAC__StreamMetadata* object, unsigned new_num_comments)
{
    FLAC__ASSERT(0 != object);
    FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);

    if (0 == object->data.vorbis_comment.comments)
    {
        FLAC__ASSERT(object->data.vorbis_comment.num_comments == 0);
        if (0 == new_num_comments)
            return true;
        else if (0 == (object->data.vorbis_comment.comments = vorbiscomment_entry_array_new_(new_num_comments)))
            return false;
    }
    else
    {
        const size_t old_size = object->data.vorbis_comment.num_comments * sizeof(FLAC__StreamMetadata_VorbisComment_Entry);
        const size_t new_size = new_num_comments * sizeof(FLAC__StreamMetadata_VorbisComment_Entry);

        /* overflow check */
        if ((size_t)new_num_comments > SIZE_MAX / sizeof(FLAC__StreamMetadata_VorbisComment_Entry))
            return false;

        FLAC__ASSERT(object->data.vorbis_comment.num_comments > 0);

        /* if shrinking, free the truncated entries */
        if (new_num_comments < object->data.vorbis_comment.num_comments)
        {
            unsigned i;
            for (i = new_num_comments; i < object->data.vorbis_comment.num_comments; i++)
                if (0 != object->data.vorbis_comment.comments[i].entry)
                    free(object->data.vorbis_comment.comments[i].entry);
        }

        if (new_size == 0)
        {
            free(object->data.vorbis_comment.comments);
            object->data.vorbis_comment.comments = 0;
        }
        else if (0 == (object->data.vorbis_comment.comments = (FLAC__StreamMetadata_VorbisComment_Entry*)realloc(object->data.vorbis_comment.comments, new_size)))
            return false;

        /* if growing, zero all the length/pointers of new elements */
        if (new_size > old_size)
            memset(object->data.vorbis_comment.comments + object->data.vorbis_comment.num_comments, 0, new_size - old_size);
    }

    object->data.vorbis_comment.num_comments = new_num_comments;

    vorbiscomment_calculate_length_(object);
    return true;
}

FLAC_API FLAC__bool FLAC__metadata_object_vorbiscomment_set_comment(FLAC__StreamMetadata* object, unsigned comment_num, FLAC__StreamMetadata_VorbisComment_Entry entry, FLAC__bool copy)
{
    FLAC__ASSERT(0 != object);
    FLAC__ASSERT(comment_num < object->data.vorbis_comment.num_comments);

    if (!FLAC__format_vorbiscomment_entry_is_legal(entry.entry, entry.length))
        return false;
    return vorbiscomment_set_entry_(object, &object->data.vorbis_comment.comments[comment_num], &entry, copy);
}

FLAC_API FLAC__bool FLAC__metadata_object_vorbiscomment_insert_comment(FLAC__StreamMetadata* object, unsigned comment_num, FLAC__StreamMetadata_VorbisComment_Entry entry, FLAC__bool copy)
{
    FLAC__StreamMetadata_VorbisComment* vc;

    FLAC__ASSERT(0 != object);
    FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);
    FLAC__ASSERT(comment_num <= object->data.vorbis_comment.num_comments);

    if (!FLAC__format_vorbiscomment_entry_is_legal(entry.entry, entry.length))
        return false;

    vc = &object->data.vorbis_comment;

    if (!FLAC__metadata_object_vorbiscomment_resize_comments(object, vc->num_comments + 1))
        return false;

    /* move all comments >= comment_num forward one space */
    memmove(&vc->comments[comment_num + 1], &vc->comments[comment_num], sizeof(FLAC__StreamMetadata_VorbisComment_Entry) * (vc->num_comments - 1 - comment_num));
    vc->comments[comment_num].length = 0;
    vc->comments[comment_num].entry = 0;

    return FLAC__metadata_object_vorbiscomment_set_comment(object, comment_num, entry, copy);
}

FLAC_API FLAC__bool FLAC__metadata_object_vorbiscomment_append_comment(FLAC__StreamMetadata* object, FLAC__StreamMetadata_VorbisComment_Entry entry, FLAC__bool copy)
{
    FLAC__ASSERT(0 != object);
    FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);
    return FLAC__metadata_object_vorbiscomment_insert_comment(object, object->data.vorbis_comment.num_comments, entry, copy);
}

FLAC_API FLAC__bool FLAC__metadata_object_vorbiscomment_replace_comment(FLAC__StreamMetadata* object, FLAC__StreamMetadata_VorbisComment_Entry entry, FLAC__bool all, FLAC__bool copy)
{
    FLAC__ASSERT(0 != entry.entry && entry.length > 0);

    if (!FLAC__format_vorbiscomment_entry_is_legal(entry.entry, entry.length))
        return false;

    {
        int i;
        size_t field_name_length;
        const FLAC__byte* eq = (FLAC__byte*)memchr(entry.entry, '=', entry.length);

        FLAC__ASSERT(0 != eq);

        if (0 == eq)
            return false; /* double protection */

        field_name_length = eq - entry.entry;

        if ((i = vorbiscomment_find_entry_from_(object, 0, (const char*)entry.entry, field_name_length)) >= 0)
        {
            unsigned index = (unsigned)i;
            if (!FLAC__metadata_object_vorbiscomment_set_comment(object, index, entry, copy))
                return false;
            if (all && (index + 1 < object->data.vorbis_comment.num_comments))
            {
                for (i = vorbiscomment_find_entry_from_(object, index + 1, (const char*)entry.entry, field_name_length); i >= 0;)
                {
                    if (!FLAC__metadata_object_vorbiscomment_delete_comment(object, (unsigned)i))
                        return false;
                    if ((unsigned)i < object->data.vorbis_comment.num_comments)
                        i = vorbiscomment_find_entry_from_(object, (unsigned)i, (const char*)entry.entry, field_name_length);
                    else
                        i = -1;
                }
            }
            return true;
        }
        else
            return FLAC__metadata_object_vorbiscomment_append_comment(object, entry, copy);
    }
}

FLAC_API FLAC__bool FLAC__metadata_object_vorbiscomment_delete_comment(FLAC__StreamMetadata* object, unsigned comment_num)
{
    FLAC__StreamMetadata_VorbisComment* vc;

    FLAC__ASSERT(0 != object);
    FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);
    FLAC__ASSERT(comment_num < object->data.vorbis_comment.num_comments);

    vc = &object->data.vorbis_comment;

    /* free the comment at comment_num */
    if (0 != vc->comments[comment_num].entry)
        free(vc->comments[comment_num].entry);

    /* move all comments > comment_num backward one space */
    memmove(&vc->comments[comment_num], &vc->comments[comment_num + 1], sizeof(FLAC__StreamMetadata_VorbisComment_Entry) * (vc->num_comments - comment_num - 1));
    vc->comments[vc->num_comments - 1].length = 0;
    vc->comments[vc->num_comments - 1].entry = 0;

    return FLAC__metadata_object_vorbiscomment_resize_comments(object, vc->num_comments - 1);
}

FLAC_API FLAC__bool FLAC__metadata_object_vorbiscomment_entry_from_name_value_pair(FLAC__StreamMetadata_VorbisComment_Entry* entry, const char* field_name, const char* field_value)
{
    FLAC__ASSERT(0 != entry);
    FLAC__ASSERT(0 != field_name);
    FLAC__ASSERT(0 != field_value);

    if (!FLAC__format_vorbiscomment_entry_name_is_legal(field_name))
        return false;
    if (!FLAC__format_vorbiscomment_entry_value_is_legal((const FLAC__byte*)field_value, (unsigned)(-1)))
        return false;

    {
        const size_t nn = strlen(field_name);
        const size_t nv = strlen(field_value);
        entry->length = nn + 1 /*=*/ + nv;
        if (0 == (entry->entry = (FLAC__byte*)safe_malloc_add_4op_(nn, /*+*/ 1, /*+*/ nv, /*+*/ 1)))
            return false;
        memcpy(entry->entry, field_name, nn);
        entry->entry[nn] = '=';
        memcpy(entry->entry + nn + 1, field_value, nv);
        entry->entry[entry->length] = '\0';
    }

    return true;
}

FLAC_API FLAC__bool FLAC__metadata_object_vorbiscomment_entry_to_name_value_pair(const FLAC__StreamMetadata_VorbisComment_Entry entry, char** field_name, char** field_value)
{
    FLAC__ASSERT(0 != entry.entry && entry.length > 0);
    FLAC__ASSERT(0 != field_name);
    FLAC__ASSERT(0 != field_value);

    if (!FLAC__format_vorbiscomment_entry_is_legal(entry.entry, entry.length))
        return false;

    {
        const FLAC__byte* eq = (FLAC__byte*)memchr(entry.entry, '=', entry.length);
        const size_t nn = eq - entry.entry;
        const size_t nv = entry.length - nn - 1; /* -1 for the '=' */
        FLAC__ASSERT(0 != eq);
        if (0 == eq)
            return false; /* double protection */
        if (0 == (*field_name = (char*)safe_malloc_add_2op_(nn, /*+*/ 1)))
            return false;
        if (0 == (*field_value = (char*)safe_malloc_add_2op_(nv, /*+*/ 1)))
        {
            free(*field_name);
            return false;
        }
        memcpy(*field_name, entry.entry, nn);
        memcpy(*field_value, entry.entry + nn + 1, nv);
        (*field_name)[nn] = '\0';
        (*field_value)[nv] = '\0';
    }

    return true;
}

FLAC_API FLAC__bool FLAC__metadata_object_vorbiscomment_entry_matches(const FLAC__StreamMetadata_VorbisComment_Entry entry, const char* field_name, unsigned field_name_length)
{
    FLAC__ASSERT(0 != entry.entry && entry.length > 0);
    {
        const FLAC__byte* eq = (FLAC__byte*)memchr(entry.entry, '=', entry.length);
        #if defined _MSC_VER || defined __BORLANDC__ || defined __MINGW32__ || defined __EMX__
    #define FLAC__STRNCASECMP _strnicmp
        #else
    #define FLAC__STRNCASECMP strncasecmp
        #endif
        return (0 != eq && (unsigned)(eq - entry.entry) == field_name_length && 0 == FLAC__STRNCASECMP(field_name, (const char*)entry.entry, field_name_length));
        #undef FLAC__STRNCASECMP
    }
}

FLAC_API int FLAC__metadata_object_vorbiscomment_find_entry_from(const FLAC__StreamMetadata* object, unsigned offset, const char* field_name)
{
    FLAC__ASSERT(0 != field_name);

    return vorbiscomment_find_entry_from_(object, offset, field_name, strlen(field_name));
}

FLAC_API int FLAC__metadata_object_vorbiscomment_remove_entry_matching(FLAC__StreamMetadata* object, const char* field_name)
{
    const unsigned field_name_length = strlen(field_name);
    unsigned i;

    FLAC__ASSERT(0 != object);
    FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);

    for (i = 0; i < object->data.vorbis_comment.num_comments; i++)
    {
        if (FLAC__metadata_object_vorbiscomment_entry_matches(object->data.vorbis_comment.comments[i], field_name, field_name_length))
        {
            if (!FLAC__metadata_object_vorbiscomment_delete_comment(object, i))
                return -1;
            else
                return 1;
        }
    }

    return 0;
}

FLAC_API int FLAC__metadata_object_vorbiscomment_remove_entries_matching(FLAC__StreamMetadata* object, const char* field_name)
{
    FLAC__bool ok = true;
    unsigned matching = 0;
    const unsigned field_name_length = strlen(field_name);
    int i;

    FLAC__ASSERT(0 != object);
    FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);

    /* must delete from end to start otherwise it will interfere with our iteration */
    for (i = (int)object->data.vorbis_comment.num_comments - 1; ok && i >= 0; i--)
    {
        if (FLAC__metadata_object_vorbiscomment_entry_matches(object->data.vorbis_comment.comments[i], field_name, field_name_length))
        {
            matching++;
            ok &= FLAC__metadata_object_vorbiscomment_delete_comment(object, (unsigned)i);
        }
    }

    return ok ? (int)matching : -1;
}

FLAC_API FLAC__StreamMetadata_CueSheet_Track * FLAC__metadata_object_cuesheet_track_new()
{
    return (FLAC__StreamMetadata_CueSheet_Track*)calloc(1, sizeof(FLAC__StreamMetadata_CueSheet_Track));
}

FLAC_API FLAC__StreamMetadata_CueSheet_Track * FLAC__metadata_object_cuesheet_track_clone(const FLAC__StreamMetadata_CueSheet_Track* object)
{
    FLAC__StreamMetadata_CueSheet_Track* to;

    FLAC__ASSERT(0 != object);

    if (0 != (to = FLAC__metadata_object_cuesheet_track_new()))
    {
        if (!copy_track_(to, object))
        {
            FLAC__metadata_object_cuesheet_track_delete(to);
            return 0;
        }
    }

    return to;
}

void FLAC__metadata_object_cuesheet_track_delete_data(FLAC__StreamMetadata_CueSheet_Track* object)
{
    FLAC__ASSERT(0 != object);

    if (0 != object->indices)
    {
        FLAC__ASSERT(object->num_indices > 0);
        free(object->indices);
    }
}

FLAC_API void FLAC__metadata_object_cuesheet_track_delete(FLAC__StreamMetadata_CueSheet_Track* object)
{
    FLAC__metadata_object_cuesheet_track_delete_data(object);
    free(object);
}

FLAC_API FLAC__bool FLAC__metadata_object_cuesheet_track_resize_indices(FLAC__StreamMetadata* object, unsigned track_num, unsigned new_num_indices)
{
    FLAC__StreamMetadata_CueSheet_Track* track;
    FLAC__ASSERT(0 != object);
    FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_CUESHEET);
    FLAC__ASSERT(track_num < object->data.cue_sheet.num_tracks);

    track = &object->data.cue_sheet.tracks[track_num];

    if (0 == track->indices)
    {
        FLAC__ASSERT(track->num_indices == 0);
        if (0 == new_num_indices)
            return true;
        else if (0 == (track->indices = cuesheet_track_index_array_new_(new_num_indices)))
            return false;
    }
    else
    {
        const size_t old_size = track->num_indices * sizeof(FLAC__StreamMetadata_CueSheet_Index);
        const size_t new_size = new_num_indices * sizeof(FLAC__StreamMetadata_CueSheet_Index);

        /* overflow check */
        if ((size_t)new_num_indices > SIZE_MAX / sizeof(FLAC__StreamMetadata_CueSheet_Index))
            return false;

        FLAC__ASSERT(track->num_indices > 0);

        if (new_size == 0)
        {
            free(track->indices);
            track->indices = 0;
        }
        else if (0 == (track->indices = (FLAC__StreamMetadata_CueSheet_Index*)realloc(track->indices, new_size)))
            return false;

        /* if growing, zero all the lengths/pointers of new elements */
        if (new_size > old_size)
            memset(track->indices + track->num_indices, 0, new_size - old_size);
    }

    track->num_indices = new_num_indices;

    cuesheet_calculate_length_(object);
    return true;
}

FLAC_API FLAC__bool FLAC__metadata_object_cuesheet_track_insert_index(FLAC__StreamMetadata* object, unsigned track_num, unsigned index_num, FLAC__StreamMetadata_CueSheet_Index index)
{
    FLAC__StreamMetadata_CueSheet_Track* track;

    FLAC__ASSERT(0 != object);
    FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_CUESHEET);
    FLAC__ASSERT(track_num < object->data.cue_sheet.num_tracks);
    FLAC__ASSERT(index_num <= object->data.cue_sheet.tracks[track_num].num_indices);

    track = &object->data.cue_sheet.tracks[track_num];

    if (!FLAC__metadata_object_cuesheet_track_resize_indices(object, track_num, track->num_indices + 1))
        return false;

    /* move all indices >= index_num forward one space */
    memmove(&track->indices[index_num + 1], &track->indices[index_num], sizeof(FLAC__StreamMetadata_CueSheet_Index) * (track->num_indices - 1 - index_num));

    track->indices[index_num] = index;
    cuesheet_calculate_length_(object);
    return true;
}

FLAC_API FLAC__bool FLAC__metadata_object_cuesheet_track_insert_blank_index(FLAC__StreamMetadata* object, unsigned track_num, unsigned index_num)
{
    FLAC__StreamMetadata_CueSheet_Index index;
    memset(&index, 0, sizeof(index));
    return FLAC__metadata_object_cuesheet_track_insert_index(object, track_num, index_num, index);
}

FLAC_API FLAC__bool FLAC__metadata_object_cuesheet_track_delete_index(FLAC__StreamMetadata* object, unsigned track_num, unsigned index_num)
{
    FLAC__StreamMetadata_CueSheet_Track* track;

    FLAC__ASSERT(0 != object);
    FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_CUESHEET);
    FLAC__ASSERT(track_num < object->data.cue_sheet.num_tracks);
    FLAC__ASSERT(index_num < object->data.cue_sheet.tracks[track_num].num_indices);

    track = &object->data.cue_sheet.tracks[track_num];

    /* move all indices > index_num backward one space */
    memmove(&track->indices[index_num], &track->indices[index_num + 1], sizeof(FLAC__StreamMetadata_CueSheet_Index) * (track->num_indices - index_num - 1));

    FLAC__metadata_object_cuesheet_track_resize_indices(object, track_num, track->num_indices - 1);
    cuesheet_calculate_length_(object);
    return true;
}

FLAC_API FLAC__bool FLAC__metadata_object_cuesheet_resize_tracks(FLAC__StreamMetadata* object, unsigned new_num_tracks)
{
    FLAC__ASSERT(0 != object);
    FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_CUESHEET);

    if (0 == object->data.cue_sheet.tracks)
    {
        FLAC__ASSERT(object->data.cue_sheet.num_tracks == 0);
        if (0 == new_num_tracks)
            return true;
        else if (0 == (object->data.cue_sheet.tracks = cuesheet_track_array_new_(new_num_tracks)))
            return false;
    }
    else
    {
        const size_t old_size = object->data.cue_sheet.num_tracks * sizeof(FLAC__StreamMetadata_CueSheet_Track);
        const size_t new_size = new_num_tracks * sizeof(FLAC__StreamMetadata_CueSheet_Track);

        /* overflow check */
        if ((size_t)new_num_tracks > SIZE_MAX / sizeof(FLAC__StreamMetadata_CueSheet_Track))
            return false;

        FLAC__ASSERT(object->data.cue_sheet.num_tracks > 0);

        /* if shrinking, free the truncated entries */
        if (new_num_tracks < object->data.cue_sheet.num_tracks)
        {
            unsigned i;
            for (i = new_num_tracks; i < object->data.cue_sheet.num_tracks; i++)
                if (0 != object->data.cue_sheet.tracks[i].indices)
                    free(object->data.cue_sheet.tracks[i].indices);
        }

        if (new_size == 0)
        {
            free(object->data.cue_sheet.tracks);
            object->data.cue_sheet.tracks = 0;
        }
        else if (0 == (object->data.cue_sheet.tracks = (FLAC__StreamMetadata_CueSheet_Track*)realloc(object->data.cue_sheet.tracks, new_size)))
            return false;

        /* if growing, zero all the lengths/pointers of new elements */
        if (new_size > old_size)
            memset(object->data.cue_sheet.tracks + object->data.cue_sheet.num_tracks, 0, new_size - old_size);
    }

    object->data.cue_sheet.num_tracks = new_num_tracks;

    cuesheet_calculate_length_(object);
    return true;
}

FLAC_API FLAC__bool FLAC__metadata_object_cuesheet_set_track(FLAC__StreamMetadata* object, unsigned track_num, FLAC__StreamMetadata_CueSheet_Track* track, FLAC__bool copy)
{
    FLAC__ASSERT(0 != object);
    FLAC__ASSERT(track_num < object->data.cue_sheet.num_tracks);

    return cuesheet_set_track_(object, object->data.cue_sheet.tracks + track_num, track, copy);
}

FLAC_API FLAC__bool FLAC__metadata_object_cuesheet_insert_track(FLAC__StreamMetadata* object, unsigned track_num, FLAC__StreamMetadata_CueSheet_Track* track, FLAC__bool copy)
{
    FLAC__StreamMetadata_CueSheet* cs;

    FLAC__ASSERT(0 != object);
    FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_CUESHEET);
    FLAC__ASSERT(track_num <= object->data.cue_sheet.num_tracks);

    cs = &object->data.cue_sheet;

    if (!FLAC__metadata_object_cuesheet_resize_tracks(object, cs->num_tracks + 1))
        return false;

    /* move all tracks >= track_num forward one space */
    memmove(&cs->tracks[track_num + 1], &cs->tracks[track_num], sizeof(FLAC__StreamMetadata_CueSheet_Track) * (cs->num_tracks - 1 - track_num));
    cs->tracks[track_num].num_indices = 0;
    cs->tracks[track_num].indices = 0;

    return FLAC__metadata_object_cuesheet_set_track(object, track_num, track, copy);
}

FLAC_API FLAC__bool FLAC__metadata_object_cuesheet_insert_blank_track(FLAC__StreamMetadata* object, unsigned track_num)
{
    FLAC__StreamMetadata_CueSheet_Track track;
    memset(&track, 0, sizeof(track));
    return FLAC__metadata_object_cuesheet_insert_track(object, track_num, &track, /*copy=*/ false);
}

FLAC_API FLAC__bool FLAC__metadata_object_cuesheet_delete_track(FLAC__StreamMetadata* object, unsigned track_num)
{
    FLAC__StreamMetadata_CueSheet* cs;

    FLAC__ASSERT(0 != object);
    FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_CUESHEET);
    FLAC__ASSERT(track_num < object->data.cue_sheet.num_tracks);

    cs = &object->data.cue_sheet;

    /* free the track at track_num */
    if (0 != cs->tracks[track_num].indices)
        free(cs->tracks[track_num].indices);

    /* move all tracks > track_num backward one space */
    memmove(&cs->tracks[track_num], &cs->tracks[track_num + 1], sizeof(FLAC__StreamMetadata_CueSheet_Track) * (cs->num_tracks - track_num - 1));
    cs->tracks[cs->num_tracks - 1].num_indices = 0;
    cs->tracks[cs->num_tracks - 1].indices = 0;

    return FLAC__metadata_object_cuesheet_resize_tracks(object, cs->num_tracks - 1);
}

FLAC_API FLAC__bool FLAC__metadata_object_cuesheet_is_legal(const FLAC__StreamMetadata* object, FLAC__bool check_cd_da_subset, const char** violation)
{
    FLAC__ASSERT(0 != object);
    FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_CUESHEET);

    return FLAC__format_cuesheet_is_legal(&object->data.cue_sheet, check_cd_da_subset, violation);
}

static FLAC__uint64 get_index_01_offset_(const FLAC__StreamMetadata_CueSheet* cs, unsigned track)
{
    if (track >= (cs->num_tracks - 1) || cs->tracks[track].num_indices < 1)
        return 0;
    else if (cs->tracks[track].indices[0].number == 1)
        return cs->tracks[track].indices[0].offset + cs->tracks[track].offset + cs->lead_in;
    else if (cs->tracks[track].num_indices < 2)
        return 0;
    else if (cs->tracks[track].indices[1].number == 1)
        return cs->tracks[track].indices[1].offset + cs->tracks[track].offset + cs->lead_in;
    else
        return 0;
}

static FLAC__uint32 cddb_add_digits_(FLAC__uint32 x)
{
    FLAC__uint32 n = 0;
    while (x)
    {
        n += (x % 10);
        x /= 10;
    }
    return n;
}

/*@@@@add to tests*/
FLAC_API FLAC__uint32 FLAC__metadata_object_cuesheet_calculate_cddb_id(const FLAC__StreamMetadata* object)
{
    const FLAC__StreamMetadata_CueSheet* cs;

    FLAC__ASSERT(0 != object);
    FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_CUESHEET);

    cs = &object->data.cue_sheet;

    if (cs->num_tracks < 2) /* need at least one real track and the lead-out track */
        return 0;

    {
        FLAC__uint32 i, length, sum = 0;
        for (i = 0; i < (cs->num_tracks - 1); i++) /* -1 to avoid counting the lead-out */
            sum += cddb_add_digits_((FLAC__uint32)(get_index_01_offset_(cs, i) / 44100));
        length = (FLAC__uint32)((cs->tracks[cs->num_tracks - 1].offset + cs->lead_in) / 44100) - (FLAC__uint32)(get_index_01_offset_(cs, 0) / 44100);

        return (sum % 0xFF) << 24 | length << 8 | (FLAC__uint32)(cs->num_tracks - 1);
    }
}

FLAC_API FLAC__bool FLAC__metadata_object_picture_set_mime_type(FLAC__StreamMetadata* object, char* mime_type, FLAC__bool copy)
{
    char* old;
    size_t old_length, new_length;

    FLAC__ASSERT(0 != object);
    FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_PICTURE);
    FLAC__ASSERT(0 != mime_type);

    old = object->data.picture.mime_type;
    old_length = old ? strlen(old) : 0;
    new_length = strlen(mime_type);

    /* do the copy first so that if we fail we leave the object untouched */
    if (copy)
    {
        if (new_length >= SIZE_MAX) /* overflow check */
            return false;
        if (!copy_bytes_((FLAC__byte**)(&object->data.picture.mime_type), (FLAC__byte*)mime_type, new_length + 1))
            return false;
    }
    else
    {
        object->data.picture.mime_type = mime_type;
    }

    if (0 != old)
        free(old);

    object->length -= old_length;
    object->length += new_length;
    return true;
}

FLAC_API FLAC__bool FLAC__metadata_object_picture_set_description(FLAC__StreamMetadata* object, FLAC__byte* description, FLAC__bool copy)
{
    FLAC__byte* old;
    size_t old_length, new_length;

    FLAC__ASSERT(0 != object);
    FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_PICTURE);
    FLAC__ASSERT(0 != description);

    old = object->data.picture.description;
    old_length = old ? strlen((const char*)old) : 0;
    new_length = strlen((const char*)description);

    /* do the copy first so that if we fail we leave the object untouched */
    if (copy)
    {
        if (new_length >= SIZE_MAX) /* overflow check */
            return false;
        if (!copy_bytes_(&object->data.picture.description, description, new_length + 1))
            return false;
    }
    else
    {
        object->data.picture.description = description;
    }

    if (0 != old)
        free(old);

    object->length -= old_length;
    object->length += new_length;
    return true;
}

FLAC_API FLAC__bool FLAC__metadata_object_picture_set_data(FLAC__StreamMetadata* object, FLAC__byte* data, FLAC__uint32 length, FLAC__bool copy)
{
    FLAC__byte* old;

    FLAC__ASSERT(0 != object);
    FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_PICTURE);
    FLAC__ASSERT((0 != data && length > 0) || (0 == data && length == 0 && copy == false));

    old = object->data.picture.data;

    /* do the copy first so that if we fail we leave the object untouched */
    if (copy)
    {
        if (!copy_bytes_(&object->data.picture.data, data, length))
            return false;
    }
    else
    {
        object->data.picture.data = data;
    }

    if (0 != old)
        free(old);

    object->length -= object->data.picture.data_length;
    object->data.picture.data_length = length;
    object->length += length;
    return true;
}

FLAC_API FLAC__bool FLAC__metadata_object_picture_is_legal(const FLAC__StreamMetadata* object, const char** violation)
{
    FLAC__ASSERT(0 != object);
    FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_PICTURE);

    return FLAC__format_picture_is_legal(&object->data.picture, violation);
}